(4x+5)(2x+10)=0

Solution for (4x+5)(2x+10)=0 equation:

(4x+5)(2x+10)=0

We multiply parentheses ..

(+8x^2+40x+10x+50)=0

We get rid of parentheses

8x^2+40x+10x+50=0

We add all the numbers together, and all the variables

8x^2+50x+50=0

a = 8; b = 50; c = +50;
Δ = b2-4ac
Δ = 502-4·8·50
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(50)-30}{2*8}=\frac{-80}{16}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(50)+30}{2*8}=\frac{-20}{16}
=-1+1/4
$